Wireless communication technologies are widely used in nowadays. FIG. 1A illustrates the schematic view of a conventional wireless communication system 1. In the conventional wireless communication system 1, a first mobile apparatus 11 connects with a base station 13 via a channel 17. Please refer to FIG. 1B at the same time, FIG. 1B illustrates a schematic view of the channel 17. The channel 17 comprises a plurality of resource blocks 171. Each of the resource blocks 171 comprises a plurality of sub-blocks 173. Further, a plurality of sequences 175 can be defined in each of the sub-blocks 173, and the sequences 175 may have good correlation property among each other.
When the first mobile apparatus 11 needs to obtain the usage of the uplink bandwidth provided by the base station 13, the mobile 11 chooses one of the sequences 175 randomly and transmits the sequence 175 in one of the sub-block 173. Rest spaces 177 in the sub-block 173 can be used to transmit an access message which includes some additional information such as used identifier etc. In such mechanism, if there is no other user requesting for the bandwidth in the sub-block 173 chosen by the first mobile apparatus 11, the base station 13 can decode the access message directly and reply the decision of requesting the bandwidth to the first mobile apparatus 11.
However, if a second mobile apparatus which needs to obtain the usage of the uplink bandwidth provided by the base station 13 uses the same sub-block 173 used by the first mobile apparatus 13, it is difficult for the base station 13 to decode the access messages from the first mobile apparatus 11 and the second mobile apparatus since the access messages may be collided in the same sub-block 173.
Since both the first mobile apparatus 11 and the second mobile apparatus choose the sequence randomly, they may choose the same sequence 175 in the same sub-block 173. Accordingly, the base station 13 can misunderstand that there is only one mobile apparatus requesting for the bandwidth so that result in a system error.
Moreover, in order to identify the different mobile apparatus, the access message from the mobile apparatus needs to comprise an identifier so that the base station 13 can recognize the different mobile apparatus. However, comprising the identifier causes the reduction of the usable spaces of the access message.
Therefore, a mechanism for addressing the above problems is needed.